Method of packaging pulverulent material



Oct. 12, 1965 c. w. VOGT 3,211,190

METHOD OF PACKAGING PULVERULENT MATERIAL Filed June 5, 1963 3 Sheets-Sheet 1 GAS PRESSURE SUC T/ON' J 1 INVENTOR. jg CLARENCE W V067 JV A fiq/e/w/J Oct. 12, 1965 c. w. VOGT METHOD OF PACKAGING PULVERULENI MATERIAL 5 Sheets-Sheet Filed June 5, 1963 k; y m A S Y 1 ,my a ,,m!

uwmvrox CLARE/var W. V067 j A va/avers.

United States Patent 3,211,190 METHOD OF PACKAGING PULVERULENT MATERIAL Clarence W. Vogt, Box 232, Westport, Conn. Filed June 5, 1963, Ser. No. 287,173 6 Claims. (Cl. 1415) This invention relates to the art of packaging and more particularly to the method of packaging molda-ble, pulverulent or other non-form-retaining materials.

This application is a continuation-in-part of my application Serial No. 743,041, filed June 19, 1958, now abandoned, which application, in turn, is a continuation-inpart of my application Serial No. 556, 158, filed Dec. 27, 1955, and now abandoned.

As conducive to an understanding of the invention, it is noted that in packaging such commodities as flour, pancake, cake mixes, and the like, When such commodities are sifted or poured into a bag or container, the interstitial spaces between the particles and the head room resulting from the settling of the commodity after it is packed, results in an overall package size much larger than would normally be required if such interstitial spaces and head room were eliminated, with resultant need for greater shelf space and greater cost of packaging material.

Furthermore, due to the adverse effect on certain materials of the air with its entrained water vapor collected in such interstitial spaces and head room, wide variation may occur in the shelf life of packages of the same commodity thereby limiting the formulation of the materials that can be packaged or the time of storage that may be tolerated.

It has been proposed to fill containers by other methods than merely pouring a given weight of material into a flexible bag or inflexible container such as a carton or box. For example, apparatus has been made which includes mechanism for creating a reduced pressure in the container and permitting atmospheric pressure to force fluent or non form-retaining material into the container. Such apparatus is not capable of filling a container with densely packed material, even when it is subjected to repeated applications of reduced pressure. Moreover, the apparatus is not very suitable for filling bags or other flexible containers for the reason that the reduced pressure within the containers causes their partial collapse unless a higher vacuum is maintained around their exteriors. This entails complications in the structure of the filling apparatus which result in poorly formed packages.

It has also been suggested that porous containers can be filled by entraining finely-divided or light-weight material in a stream of air and blowing the entrained material into the container while allowing the air to flow out through the pores in the container. In practice, the container cannot be filled completely or the material packed densely therein by such an entraining operation and, moreover, an excessively long time is required to fill such a porous container only partially.

Other methods using positive gas pressure for blowing finely-divided material into a container, such as for example, methods of blowing core sand into core boxes have not been deemed useful for filling bags, cartons, boxes and An object of the invention is to provide a method for forming packages containing materials of the above type, in such manner that the finished package will be substantially devoid of interstitial spaces and head room and hence will contain a minimum amount of air and entrained water vapor and will be of minimum size for a given weight of material, thereby occupying a minimum of shelf space, shipping bulk and container material with resultant lowered cost of storage, handling and packaging.

According to the present invention, a. filling head is provided which may be positioned in sealing engagement with the mouth of the container to be charged, the head being provided with a hopper or magazine having an outlet in communication with the container. By means of a gas under pressure applied to the material in the hopper, a charge of such material will be forced into the container in compacted form. Suitable vents are provided in the filling head through which the air in the container may be discharged without loss of any of the material being forced into the container. The package thus formed will have a minimum of interstitial spaces and a minimum of volume for a given weight.

The container according to the invention may be formed from a wrapper provided with a reinforcing strip of cardboard, heavy paper, relatively stiff plastic or the like, having a side conforming to and coextensive with one side and ends conforming to and coextensive with the opposite ends of a package of prismatic shape, such as a six sided package of rectangular or square cross section. In addition, the strip has end flaps which are folded over the strip ends at the ends of the package. Preferably the junctions between the side and the ends of the strip are formed by a pair of spaced score lines as are the junctions between the end flaps and the ends of the strip and in a preferred embodiment the end flaps are transversely corrugated to facilitate folding at different locations.

The wrapper is folded to extend at substantially right angles to the sides of the reinforcing strip and end folds of the wrapper extending laterally of the outstanding end portion of the reinforcing strip are held together so that the partially closed wrapper will form a trough into which the non-form-retaining material may be introduced in compacted form if desired, the trough-like container and reinforcing strip acting to retain and support the material during completion of the wrapping operation. The prismatic desirably parallelepiped sealed packages thus formed will have excellent resistance to deformation without regard to the form retaining properties of the material being packaged.

In the accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention,

FIGURE 1 is a fragmentary sectional view of the filling equipment,

FIGURE 2 is a view taken along line 2-2 of FIG URE 1,

FIGURE 3 is a plan view of a wrapper accordin to one embodiment of the invention,

FIGURE 4 is a perspective view of a portion of a partially completed package illustrating the trough-like conformation of the wrapper for filling,

FIGURE 5 is a perspective view of the partially completed package showing the fin seal at one edge thereof,

FIGURES 6 and 7 are perspective views of the package in further stages of its formation,

FIGURE 8 is a fragmentary sectional View illustrating another method of filling,

FIGURES 9 and 10 are plan views of a wrapper according to another embodiment of the invention,

FIGURE 11 is a fragmentary sectional view illustrating a step in the formation of a package utilizing the wrapper of FIGURES 9 and 10.

FIGURES 12, 13 and 14 are perspective views of the package utilizing the wrapper of FIGURES 9 and 10 in various further stages of its formation, and

FIGURE is a perspective view similar to FIGURE '14 showing the fin seals bent downwardly, in the completed package.

Referring now to the drawings, in FIGURES l and 2 is illustratively shown an apparatus for forming packages of the above type.

The apparatus may comprise a mold 11 having a bottom portion 12 and a head portion 13. The bottom portion desirably has a pair of spaced parallel side walls 14 (FIGURE 11), and end walls 15 positioned between the side walls and pivotally mounted so as to move through a slight angle of say 15 degrees to substantially vertical position as diagrammatically illustrated by the double headed arrow 16 in FIGURE 1. Each of the end walls 15 has a passageway 17 extending through its top surface 18 and through its inner surface 19 and suitable means (not shown) are provided to apply suction in said passageway. Similar suction means are also provided in side walls 14 (FIGURE '11).

The floor of the rectangular cavity C defined by the side and end walls 14 and 15 may comprise a rectangular plunger 21 which may be adjusted vertically in said cavity as diagrammatically represented by the double headed arrow 22 shown in FIGURE 1 to determine the height of the package to be formed.

The head 13 of the mold 11 desirably comprises a substantially rectangular block 25 of greater length and width than the corresponding dimensions of the cavity C. Affixed to the undersurface of block 25 as by bonding, is a sheet 26 of resilient material illustratively of rubber, of dimensions such that its ends and sides will overlie the upper surfaces of the side and end walls 14 and 15 of the mold when the latter is closed to effect a seal in the manner hereinafter described.

The block 25 has a plurality of recesses 27 therein, illustratively two in number, which are adapted to be aligned with the cavity C in the mold when the latter is closed. The recesses 27 are connected by passageways 28 in the block 25 which lead to the exterior thereof, defining a port 29, and a nozzle 31 is provided, normally spaced from said port 29, to be moved thereagainst to blow a jet of gas therethrough.

Positioned over each of the recesses 27 is a perforated plate 32, having a screen 33 thereon having relatively fine openings therethrough, said plate and said screen being secured to the undersurface of the head 25 as by screws 34, the sheet 26 having openings 35 to accommodate the plates and screens as is shown in FIGURES l and 2.

The block 25 desirably has an annular hub 38 on its top surface which encompasses a conical cavity 39 in said block, the apex of said cavity having an opening 41 aligned with a corresponding opening 42 in sheet 26. The hub 38 serves as the support for a magazine or hopper 43, illustratively a sleeve which may be charged in any suitable manner with material with which the package is to be filled and suitable means (not shown) are provided to apply a source of gas under pressure to the column of material in the sleeve 43.

The head 13 is suitably mounted so that it may be moved vertically against the top of the bottom portion 12 and also may be moved laterally away from said bottom portion 12. This movement is diagrammatically represented by the arrows 44 shown in FIGURE 1.

A typical wrapper for use with the equipment above described is of the same general type as that shown in my co-pending application Serial No. 550,412, filed Dec. 1, 1955, now abandoned. This wrapper for use in the preparation of prism shaped packages of material such as moldable, pulverulent or other non-formretaining material such as flour, powdered cake mixes, crust mixes or the like, may be of the type shown at W in FIGURE 3 and consists of a generally rectangular sheet 51 of suitable plastic or paper, coated or impregnated with thermoplastic resin such as Saran, polyethylene or polyvinyl resin or wax. The sheet 51 carries on one surface a reinforcing strip S of thin cardboard or similar relatively stiff material, which is adhesively secured to the sheet 51 and extends the length thereof between its side edges 52, 53 and protrudes beyond the end edges 54.

The strip S has spaced pairs of double score or fold lines X and Y and X, Y near each end, the double score lines X and X being positioned inwardly of the end edges 54- of the sheet 51 and spaced by a distance substantially equal to the length of one side of the package, the width of the strip S being co-extensive with that of the side of the package along which it extends. Each of the double score lines Y, Y extends beyond the associated end edge 54 of the sheet by an amount slightly less than the distance between the end edge 54 and the associated fold or score line X, X and is spaced from the associated score lines X and X respectively, by a distance substantially equal to the height of the package. The portion 55 of the strip S at each end thereof defines a flap and preferably such flaps are transversely corrugated as at 56.

In the embodiment shown in FIGURE 3, the reinforcing strip S is offset from the center of the sheet 51 and the portions 51a on each side of the strip S comprise two opposed sides of the finished package; the portion 51b on the side of one of the portions 51a, comprises the side of the package opposed to the reinforcing strip S and the portions 510 adjacent the side edges 52 and 53 of the sheet 51 form sealing flaps.

In the embodiment shown in FIGURES 9 and 10 which correspond in many respects to the embodiment shown in FIGURE 3 with corresponding parts having the same reference numerals primed, the wrapper W is provided with a reinforcing strip S that is centrally located on the sheet 51 and the portions 51a on each side of the strip S form two opposed sides of the finished package, the portions 51's adjacent the side edges 52' and 53' of the sheet 51 forming sealing flaps. The package formed by the wrapper W has the side thereof opposed to strip S formed by a separate rectangular cover sheet 61 (FIGURE 10) of length substantially the same as that of sheet 51. The portion 61a of cover sheet 61 on each side of the central portion 61]) thereof, which is substantially the same width as that of strip S, define sealing flaps which will be connected to flaps 51'c in the manner hereinafter described.

It will be understood that the sheets 51 and 51 with the reinforcing strips S and S thereon as well as the cover sheet 61 may be a separate article or a series of such sheets may be formed side to side to form a continuous roll or an accordian or fan-fold assembly from which the wrapper may be supplied to the packaging equipment.

The initial steps of forming a package with the equipment above described is the same whether the wrapper W or W is utilized and the operation will be first described with respect to the wrapper W shown in FIG- URE 3. Thus, the plunger 21 is raised so that it is substantially flush with the top surfaces of the side walls 14 of the mold and the end walls 15 are pivoted outwardly.

A sheet 51 is positioned over the plunger 21 with the reinforcing strip S uppermost and with the portion thereof between score lines X and X aligned with the length of the plunger. The sheet 51 is then pressed downwardly against the plunger 21 which is lowered an amount depending upon the height of the package desired.

The pivoted end walls 15 may then be moved inwardly to the vertical position shown in FIGURE 1 and the substantially rectangular cavity C in the mold will be lined with the portions 51a of the wrapper W on opposed sides thereof; the strip S and associated portion of the wrapper will be adjacent the plunger 21; the flap 51c adjacent side edge 52 and the portion 51b and associated flap 510 will extend beyond the top surface of the side walls 14 and the portions of the wrapper adjacent the end edges 54 thereof will be against the end walls 15. Thus, the wrapper W will be formed into substantially a trough-like container.

Portions 65 of the wrapper W laterally of the end 66 thereof, as shown in FIGURE 4, form corners which are tightly clamped together for preventing leakage of material from the trough-like container formed by the partially folded wrapper. The portion 51b and flaps 51c of the wrapper extending beyond the top surface 'of side walls 14 of the mold and the ends of the strip S extending beyond the end walls 15 may then be bent outwardly at substantially right angles by any suitable means.

Suction may be applied to the passageways 17 in the end and side walls 14 and 15 to retain the folded over portions of the reinforcing strip against the tops of the side and end walls 14 and 15; to retain the vertical portions of the reinforcing strip against the inner surfaces of the end walls 15 and to retain the folded over portions of the sheet against the top of the side Walls (FIG- URE 11).

The head 13 is then positioned directly over the bottom portion 12 of the mold and moved downwardly to the position shown in FIGURE 1 so that the portions of the resilient sheet 26 overlying the top surfaces of the side and end walls 14 and 15 will engage the folded over portions 510 of the sheet 51 and strip S to provide a dependable seal.

Thereupon gas under pressure is applied to the column of material in magazine or hopper 43 to force some of the material through aligned openings 41, 42 into the trough-like container defined by the partially completed wrapper. As such material enters the trough-like container, the air therein will be forced through the screens 33 and the perforated plates 32, through passageway 28 out of port 29. As the openings in screen 33 are sufficiently small to preclude the passage therethrough of any of the material being forced into the trough-like container, none of such material will escape through port 29. Consequently, the partially completed container will quickly fill and be highly compacted so that the inter stitial spaces therein will be reduced to a minimum. Thereupon the gas pressure on the charge of material in the magazine or hopper is released and the head 13 moved vertically and then laterally away from the bottom portion 12 of the mold as diagrammatically indicated by the arrows 44 in FIGURE 1.

The gas is preferably dried before application to the column of material in the magazine or hopper so that any gas that should enter the container will have a minimum of water vapor.

As a portion of the charge of material remaining in the magazine or hopper 43 has been compacted, none of such material will fall through opening 41 during and after such movement of the head 13. Thus, the material remaining in the magazine or hopper 43 remains available for a next wrapper filling operation without the loss of any material.

When the head portion 13 is vertically clear of the bottom portion 12 and before the head 13 is moved laterally, the nozzle 31 may be applied to port 29 to blow away from the screen 33 any material that may adhere thereto. It will be readily apparent from FIG- URE 1 that the entire screen 33 is in communication with a cavity of the mold during a filling operation and is utilized to its best advantage. Further, it will be readily apparent that the direction of movement of the material in its attempt to pass through the screen 33 is in one direction only. Thus, when the nozzle 31 is applied to the port 29, in a single operation the screens 33 are cleaned in their entirety and the direction of air is entirely opposite to the previous direction of material With respect to the screens 33 so that in a single operation there is a complete cleaning of all effective screen surfaces of the filler with the material removed from the screens 33 being deposited into the filled wrapper W.

The next step in the formation of the package utilizing the wrapper W is to fold the portion 51b and associated flap 51c thereof over the compacted contents in the trough-shaped container to bring both the flaps 510 into face to face relation. This may be accomplished by any suitable means such as illustratively shown and described in my co-pending application above identified.

The juxtaposed flaps may then be secured together by a heat sealing operation to form a fin seal 67 (FIGURE 5) extending along one edge of the package.

After the package has thus been sealed, it can be removed from the bottom portion 12 of the mold as by raising the plunger 21 after the end walls 15 are pivoted outwardly. The fin seal 67 may then be folded over against the top side of the package opposite the reinforcing strip as shown in FIGURE 6. The semi-completed package thus formed may then be passed between sealing shoes at opposite ends of the package which fold the projecting end 68 (FIGURE 5) of the wrapper downwardly to reversely bend the end of the reinforcing strip S as shown in FIGURE 6, and to seal such ends, leaving triangular flaps 69 at each end of the package. These flaps may then be folded inwardly as shown in FIGURE 7 and heat sealed or glued together thereby completing the package.

To form a package with the wrapper W shown in FIGURES 9 and 10, the sheet 51 is positioned over the plunger 21, in the same manner as sheet 51 and the sheet 51 is then pressed downwardly and the pivoted end walls 15 moved inwardly as previously described.

The substantially rectangular cavity C in the mold will be lined with portions 51a of the wrapper W on opposed sides thereof, the strip S and the adjacent portion of the wrapper W will be adjacent the plunger 21, the flaps 51c will extend beyond the top surface of side walls 14 and the portions of the wrapper adjacent the end edges 54 will be against the end walls 15. Thus the wrapper W will also be formed into substantially a trough-like container.

The portions 65 of the wrapper W laterally of the end 66 thereof as shown in FIGURE 12 will also form tightly clamped corners, and the flaps 51c of the wrapper W extending beyond the top surface of side walls 14 of the mold and the ends of the strip S extending beyond the end walls 15 may be then bent outwardly at substantially right angles. Suction may be applied to retain the folded over portions of the reinforcing strip S against the tops of the end walls 15; to retain the vertical portion of the reinforcing strip against the inner surfaces of the end walls and to retain the flaps 51c against the tops of the side walls.

The trough-like container thus formed with wrapper W is charged in the same manner as that formed with wrapper W and after the head 13 is moved away from the bottom portion 12, the rectangular sheet 61 (FIGURE 10) is laid over the compacted contents in the trough-like container so that the flaps 61a of sheet 61 are aligned with the flaps 51c of the wrapper W.

The juxtaposed pairs of flaps may then be secured together in any suitable manner to form fin seals 71 extending lengthwise of the top edges of the package.

The package thus formed may be removed from the mold by raising plunger 21. The fin seals 71 may then be folded over against the top side of the package opposite the reinforcing strip S as shown in FIGURE 12 or they may be folded downwardly over the sides of the package adjacent the reinforcing strip S as shown in FIGURE 15 The ends of the package may then be sealed by suitable sealing shoes in the manner described with respect to the Wrapper W to complete the package.

With the wrappers above described, by reason of the flaps 55, 55 which extend outwardly from the trough-like container in the mold cavity C as shown in FIGURE 1, when the trough is compacted with material as above described, no material will collect at the ends of the trough which might fall between the flaps 69 to prevent effective sealing thereof.

This difficulty, which is present with wrappers having the ends of their reinforcing strip terminating below the upper edge of the package and which are filled with compacted pulverulent or other non-form-retaining material, is avoided.

Furthermore, the flaps 55, 55 compensate for slight variations in the positioning of the reinforcing strip on the sheet which might cause one of the ends of the strip to be above and the other below the top of the package when it is being charged, with the difficulty above pointed out.

The double score lines in the reinforcing strip permit ready bending thereof without cracking of the strip which might occur with a single cut score line. In addition the double score lines provide sufficient give to the end walls of the package defined by the reinforcing strip to prevent buckling of such end walls as pressure is applied thereagainst in the event that such end walls should extend slightly above the end wall of the mold.

By reason of the corrugated flap, the same wrapper may be used for packages of a wide range of heights depending upon the position of the plunger 21, for the corrugations facilitate folding of the ends of the reinforcing strip and the sheet is of such width that sufficient portions of the side flaps will remain to form a dependable fin seal for packages within the given range of heights.

By reason of the compacting of the non-form-retaining material, a given weight of material will occupy a considerably smaller volume than a corresponding non-compacted weight of the same material. Thus, for certain pulverulent materials compacted at a pressure of 100 p.s.i., for example, the volume of the package may be approximately sixty percent of the volume of an equivalent weight of non-compacted material. Consequently, the amount of shelf space to store the packages is greatly reduced as is the quantity of wrapping material to form the package.

In addition, as interstitial spaces are reduced to a minimum and as there is substantially no head space, there will be little air with its entrained water vapor in the completed package which gives increased flexibility in the type and formulation of materials that can be packaged. The weight of a given volume of the material can be varied by varying the pressure of the gas applied to the material in the hopper or magazine 43. Greater pressure increases the weight of the material while lower pressures pack the material less densely.

However, pressures much more than 100 p.s.i. do not significantly increase the density of the pack, while pressures less than 30 p.s.i. decrease the filling rate and the density of the pack undesirably.

It is to be understood that the wrappers above described which may be used to form packages of a wide range of heights, may also accommodate materials which are not to be compacted. Thus as shown in FIGURE 8, a hopper 75 may be aligned with the trough-like container formed in the mold 11 and the trough may be filled with candies or the like.

Although the equipment has been shown and described with a single mold, it is of course to be understood that a plurality of molds could be provided and the hoppers or magazines thereof could be connected to a single reservoir containing the material to be packaged.

As many changes could be made in the above method, and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. The method of packaging pulverulent material for commercial distribution which comprises positioning the mouth of a vendable container beneath a restricted outlet of a hopper containing the material to be packed, effecting a seal between said outlet and said mouth, creating a pressure differential between the interior of the container and the top surface of the material to force some of the material from within the hopper through said outlet into the container while simultaneously removing air from within the container through a lower screen unit having the effective portion thereof completely overlying the container to fill the container in a single rapid material flow step with the material being in a compacted state after being placed within the container and while preventing the loss of material, relieving the pressure differential to prevent the loss of material through said outlet, slightly separating the filled container from the screen unit, and then cleaning the entire screen unit in a single back blowing of gas therethrough with all of the material removed from the screen unit being directed into the filled container.

2. The method of packaging pulverulent material for commercial distribution which comprises positioning the mouth of a vendable container beneath a restricted outlet of a hopper containing the material to be packed, effecting a seal between said outlet and said mouth, creating a pressure differential between the interior of the container and the top surface of the material to force some of the material from within the hopper through said outlet into the container while simultaneously removing air from within the container through a lower screen unit having the effective portion thereof completely overlying the container and all of the air passing said screen passing directly outwardly from within the container to fill the container in a single rapid material flow step with the material being in a compacted state after being placed within the container and while preventing the loss of material, relieving the pressure differential to prevent the loss of material through said outlet, slightly separating the filled container from the screen unit, and then cleaning the entire screen uni-t in a single back blowing of gas therethrough with all of the material removed from the screen unit being directed into the filled container.

3. The method of packaging pulverulent material for commercial distribution which comprises positioning the mouth of a vendable container beneath a restricted outlet of a hopper containing the material to be packed, effecting a seal between said outlet and said mouth, creating a pressure differential between the interior of the container and the top surface of the material to force some of the material from within the hopper through said outlet into the container while simultaneously removing air from within the container through a lower screen unit having the effective portion thereof completely overlying the container and all of the air passing said screen passing directly outwardly from within the container to fill the container in a single rapid material fiow step with the material being in a compacted state after being placed within the container and while preventing the loss of material, relieving the pressure differential to prevent the loss of material through said outlet, slightly separating the filled container from the screen unit, and then cleaning the entire screen unit in a single back blowing of gas therethrough in one direction only with all of the material removed from the screen unit being directed into the filled container.

4. The method of packaging pulverulent material for commercial distribution which comprises positioning the mouth of a vendable container beneath a restricted outlet of a hopper containing the material to be packed, effecting a seal between said outlet and said mouth, creating a pressure differential between the interior of the container and the top surface of the material to force some of the material from within the hopper through said outlet into the container while simultaneously removing r r m Within the container through a lower screen unit having the effective portion thereof completely overlying the container and all of the air passing said screen passing directly outwardly from within the container to fill the container in a single rapid material flow step with the material being in a compacted state after being placed within the container and while preventing the loss of material, relieving the pressure differential to prevent the loss of material through said out let, slightly separating the filled container from the screen unit, and then cleaning the entire screen unit in a single back blowing of gas therethrough with all of the material removed from the screen unit being directed into the filled container, removing the filled container from the hopper, substituting another empty container for the filled container, and then repeating the filling steps dispensing additional of the material from the hopper.

5. The method of packaging pulverulent material for commercial distribution which comprises positioning the mouth of a vendable container beneath a restricted outlet of a hopper containing the material to be packed, effecting a seal between said outlet and said mouth, creating a pressure differential between the interior of the container and the top surface of the material to force some of the material from within the hopper through said outlet into the container while simultaneously removing air from within the container through a lower screen unit having the effective portion thereof completely overlying the container and all of the air passing said screen passing directly outwardly from within the container to fill the container in a single rapid material flow step with the material being in a compacted state after being placed Within the container and while preventing the loss of material, relieving the pressure differential to prevent the loss of material through said outlet, slightly separating the filled container from the screen unit, and then cleaning the entire screen unit in a single back blowing of gas therethrough in one direction only with all of the material removed from the screen unit being directed into the filled container, removing the filled container from the hopper, substituting another empty container for the filled container, and then repeating the filling steps dispensing additional of the material from the hopper.

6. A filler for filling containers for commercial distribution with pulverulent material under pressure, said filler comprising a hopper having a scalable upper portion and an enlarged base, a lower discharge outlet of a reduced cross section opening through said base, a filter screen unit adjacent said discharge outlet at the lower surface of said base, air discharge passages in said base in communica-tion with said screen unit for receiving air passing therethrough, a peripheral seal on the underside of said base surrounding said discharge outlet and said screen unit and for sealing engagement by a container to be filled, means for creating a pressure differential between the interior of the container and the top surface of the material to force some of the material from within the hopper through said outlet into the container while simultaneously removing air from within the container to fill the container in a single rapid material flow step with the material being in a compacted state after being placed within the container and while preventing the loss of material, and means for introducing pressurized gas into said air discharge passages for back blowing the entire effective area of said screen unit in a single operation at the termination of a filling operation.

References Cited by the Examiner UNITED STATES PATENTS 2,170,469 8/39 Car-fer 141-89 XR 2,564,969 8/51 Goldberg 141-67 2,611,938 9/52 Hansberg. 2,642,215 6/53 Carter 141-51 XR 2,933,785 4/60 Hansberg.

LAVERNE D. GEIGER, Primary Examiner. 

1. THE METHOD OF PACKAGING PULVERULENT MATERIAL FOR COMMERCIAL DISTRIBUTION WHICH COMPRISES POSITIONING THE MOUTH OF A VENDABLE CONTAINER BENEATH A RESTRICTED OUTLET OF A HOPPER CONTAINING THE MATERIAL TO BE PACKED, EFFECTING A SEAL BETWEEN SAID OUTLET AND SAID MOUTH, CREATING A PRESSURE DIFFERENTIAL BETWEEN THE INTERIOR OF THE CONTAINER AND THE TOP SURFACE OF THE MATERIAL TO FORCE SOME OF THE MATERIAL FROM WITHIN THE HOPPER THROUGH SAID OUTLET INTO THE CONTAINER WHILE SIMULTANEOUSLY REMOVING AIR FROM WITHIN THE CONTAINER THROUGH A LOWER SCREEN UNIT HAVING THE EFFECTIVE PORTION THEREOF COMPLETELY OVERLYING THE CONTAINER TO FILL THE CONTAINER IN A SINGLE RAPID MATERIAL FLOW STEP WITH THE MATERIAL BEING IN A COMPACTED STATE AFTER BEING PLACED WITHIN THE CONTAINER AND WHILE PREVENTING THE LOSS OF MATERIAL, RELIEVING THE PRESSURE DIFFERENTIAL TO PREVENT THE LOSS OF MATERIAL THROUGH SAID OUTLET SLIGHTLY SEPARATING THE FILLED CONTAINER FROM THE SCREEN UNIT, AND THEN CLEANING THE ENTIRE SCREEN UNIT IN A SINGLE BACK BLOWING OF GAS THERETHROUGH WITH ALL OF THE MATERIAL REMOVED FROM THE SCREEN UNIT BEING DIRECTED INTO THE FILLED CONTAINER. 